High-density lipoprotein benefits beyond the cardiovascular system: a potential key role for modulating acquired immunity through cholesterol efflux

Potential role of anti-inflammatory HDL subclasses in metabolic unhealth/obesity

High-density lipoprotein (HDL) particles comprising heterogeneous subclasses of different functions exert anti-inflammatory effects by interacting with immune-response cells. However, the relationship of HDL subclasses with immune-response cells in metabolic unhealth/obesity has not been defined clearly. The purpose of this study was to delineate the relational changes of HDL subclasses with immune cells and inflammatory markers in metabolic unhealth/obesity to understand the role of anti-inflammatory HDL subclasses. A total of 316 participants were classified by metabolic health. HDL subclasses were detected by microfluidic chip electrophoresis. White blood cell (WBC) counts and lymphocytes were assessed using automatic haematology analyser. Levels of high-sensitivity C-reactive protein (hs-CRP) and interleukin 6 (IL-6) were measured. In our study, not only the distribution of HDL subclasses, but also HDL-related structural proteins changed with the deterioration of metabolic disease. Moreover, lymphocytes and inflammation factors significantly gradually increased. The level of HDL2b was negatively associated with WBC, lymphocytes and hs-CRP in multivariable linear regression analysis. In multinomial logistic regression analysis, high levels of HDL3 and low levels of HDL2b increased the probability of having an unfavourable metabolic unhealth/obesity status. We supposed that HDL2b particles may play anti-inflammation by negatively regulating lymphocytes activation. HDL2b may be a therapeutic target for future metabolic disease due to the anti-inflammatory effects.

1H-NMR Plasma Lipoproteins Profile Analysis Reveals Lipid Metabolism Alterations in HER2-Positive Breast Cancer Patients

The lipid tumour demand may shape the host metabolism adapting the circulating lipids composition to its growth and progression needs. This study aims to exploit the straightforward 1H-NMR lipoproteins analysis to investigate the alterations of the circulating lipoproteins' fractions in HER2-positive breast cancer and their modulations induced by treatments. The baseline 1H-NMR plasma lipoproteins profiles were measured in 43 HER2-positive breast cancer patients and compared with those of 28 healthy women. In a subset of 32 patients, longitudinal measurements were also performed along neoadjuvant chemotherapy, after surgery, adjuvant treatment, and during the two-year follow-up. Differences between groups were assessed by multivariate PLS-DA and by univariate analyses. The diagnostic power of lipoproteins subfractions was assessed by ROC curve, while lipoproteins time changes along interventions were investigated by ANOVA analysis. The PLS-DA model distinguished HER2-positive breast cancer patients from the control group with a sensitivity of 96.4% and specificity of 90.7%, mainly due to the differential levels of VLDLs subfractions that were significantly higher in the patients' group. Neoadjuvant chemotherapy-induced a significant drop in the HDLs after the first three months of treatment and a specific decrease in the HDL-3 and HDL-4 subfractions were found significantly associated with the pathological complete response achievement. These results indicate that HER2-positive breast cancer is characterized by a significant host lipid mobilization that could be useful for diagnostic purposes. Moreover, the lipoproteins profiles alterations induced by the therapeutic interventions could predict the clinical outcome supporting the application of 1H-NMR lipoproteins profiles analysis for longitudinal monitoring of HER2-positive breast cancer in large clinical studies.

HDL (High-Density Lipoprotein) Remodeling and Magnetic Resonance Imaging-Assessed Atherosclerotic Plaque Burden: Study in a Preclinical Experimental Model

OBJECTIVE

HDL (high-density lipoprotein) role in atherosclerosis is controversial. Clinical trials with CETP (cholesterylester transfer protein)-inhibitors have not provided benefit. We have shown that HDL remodeling in hypercholesterolemia reduces HDL cardioprotective potential. We aimed to assess whether hypercholesterolemia affects HDL-induced atherosclerotic plaque regression. Approach and Results: Atherosclerosis was induced in New Zealand White rabbits for 3-months by combining a high-fat-diet and double-balloon aortic denudation. Then, animals underwent magnetic resonance imaging (basal plaque) and randomized to receive 4 IV infusions (1 infusion/wk) of HDL isolated from normocholesterolemic (NC-HDL; 75 mg/kg; n=10), hypercholesterolemic (HC-HDL; 75 mg/Kg; n=10), or vehicle (n=10) rabbits. Then, animals underwent a second magnetic resonance imaging (end plaque). Blood, aorta, and liver samples were obtained for analyses. Follow-up magnetic resonance imaging revealed that NC-HDL administration regressed atherosclerotic lesions by 4.3%, whereas, conversely, the administration of HC-HDLs induced a further 6.5% progression (P<0.05 versus basal). Plaque characterization showed that HC-HDL administered animals had a 2-fold higher lipid and cholesterol content versus those infused NC-HDL and vehicle (P<0.05). No differences were observed among groups in CD31 levels, nor in infiltrated macrophages or smooth muscle cells. Plaques from HC-HDL administered animals exhibited higher Casp3 (caspase 3) content (P<0.05 versus vehicle and NC-HDL) whereas plaques from NC-HDL infused animals showed lower expression of Casp3, Cox1 (cyclooxygenase 1), inducible nitric oxide synthase, and MMP (metalloproteinase) activity (P<0.05 versus HC-HDL and vehicle). HDLs isolated from animals administered HC-HDL displayed lower antioxidant potential and cholesterol efflux capacity as compared with HDLs isolated from NC-HDL-infused animal and vehicle or donor HDL (P<0.05). There were no differences in HDL-ApoA1 content, ABCA1 (ATP-binding cassette transporter A1) vascular expression, and SRB1 (scavenger receptor B1) and ABCA1 liver expression.

CONCLUSIONS

HDL particles isolated from a hypercholesterolemic milieu lose their ability to regress and stabilize atherosclerotic lesions. Our data suggest that HDL remodeling in patients with co-morbidities may lead to the loss of HDL atheroprotective functions.

Analysis of platelets from a diet-induced obesity rat model: elucidating platelet dysfunction in obesity

Obesity is one of the main health problems in industrialized countries. The contribution of multiple factors developed in obesity can hardly be modeled in vitro. In this context, the development of animal models mimicking human obesity could be essential. The aim of the present study was to compare platelets from a diet-induced obesity (DIO) rat model with their lean control group in order to elucidate platelet dysfunction mechanisms in obesity and correlate the results with previous data from morbid obese patients. In parallel, we also established a blood collection and platelet isolation methodology to study the DIO rat model at biochemical and functional level. Optimal blood collection was obtained from vena cava and platelet isolation was based on a serial of centrifugations avoiding platelet activation. Our results show that the DIO rat model simulate obesity pathologically since weight gain, fasting glucose and platelet counts are increased in obese rats. Interestingly, platelet levels of the active form of Src (pTyr⁴¹⁹) showed a tendency to increase in DIO rats pointing towards a potential dysfunction in Src family kinases-related signalling pathways in obesity. Moreover, platelets from DIO rats adhere more to collagen compared with the control group, pointing towards Glycoprotein VI (GPVI) as one of the dysregulated receptors in obesity, in agreement with our recent studies in humans. These results confirm that obesity, in line with human studies, present a platelet dysregulation, and highlight the relevance of considering novel antithrombotic drug targets in these patients, such as GPVI.

Lipid efflux mechanisms, relation to disease and potential therapeutic aspects

Lipids are hydrophobic and amphiphilic molecules involved in diverse functions such as membrane structure, energy metabolism, immunity, and signaling. However, altered intra-cellular lipid levels or composition can lead to metabolic and inflammatory dysfunction, as well as lipotoxicity. Thus, intra-cellular lipid homeostasis is tightly regulated by multiple mechanisms. Since most peripheral cells do not catabolize cholesterol, efflux (extra-cellular transport) of cholesterol is vital for lipid homeostasis. Defective efflux contributes to atherosclerotic plaque development, impaired β-cell insulin secretion, and neuropathology. Of these, defective lipid efflux in macrophages in the arterial walls leading to foam cell and atherosclerotic plaque formation has been the most well studied, likely because a leading global cause of death is cardiovascular disease. Circulating high density lipoprotein particles play critical roles as acceptors of effluxed cellular lipids, suggesting their importance in disease etiology. We review here mechanisms and pathways that modulate lipid efflux, the role of lipid efflux in disease etiology, and therapeutic options aimed at modulating this critical process.

Advances in HDL: Much More than Lipid Transporters

High Density Lipoprotein (HDL) particles, beyond serving as lipid transporters and playing a key role in reverse cholesterol transport, carry a highly variable number of proteins, micro-RNAs, vitamins, and hormones, which endow them with the ability to mediate a plethora of cellular and molecular mechanisms that promote cardiovascular health. It is becoming increasingly evident, however, that the presence of cardiovascular risk factors and co-morbidities alters HDLs cargo and protective functions. This concept has led to the notion that metrics other than HDL-cholesterol levels, such as HDL functionality and composition, may better capture HDL cardiovascular protection. On the other hand, the potential of HDL as natural delivery carriers has also fostered the design of engineered HDL-mimetics aiming to improve HDL efficacy or as drug-delivery agents with therapeutic potential. In this paper, we first provide an overview of the molecules known to be transported by HDL particles and mainly discuss their functions in the cardiovascular system. Second, we describe the impact of cardiovascular risk factors and co-morbidities on HDL remodeling. Finally, we review the currently developed HDL-based approaches.

Intake of 3 Eggs per Day When Compared to a Choline Bitartrate Supplement, Downregulates Cholesterol Synthesis without Changing the LDL/HDL Ratio

Cardiovascular disease (CVD) risk is associated with high concentrations of low-density lipoprotein cholesterol (LDL-C). The impact of dietary cholesterol on plasma lipid concentrations still remains a concern. The effects of egg intake in comparison to choline bitartrate supplement was studied in a young, healthy population. Thirty participants were enrolled for a 13-week intervention. After a 2-week run-in period, subjects were randomized to consume either 3 eggs/day or a choline bitartrate supplement (~400 mg choline for both treatments) for 4-weeks each. After a 3-week washout period, they were allocated to the alternate treatment. Dietary records, plasma lipids, apolipoproteins (apo) concentrations, and peripheral blood mononuclear cell expression of regulatory genes for cholesterol homeostasis were assessed at the end of each intervention. Dietary intakes of saturated and monounsaturated fat were higher with the consumption of eggs compared to the choline period. In addition, higher plasma concentrations of total cholesterol (7.5%), high density lipoprotein cholesterol (HDL-C) (5%) and LDL-C (8.1%) were observed with egg consumption (p < 0.01), while no change was seen in LDL-C/HDL-C ratio, a key marker of heart disease risk. Compared to choline supplementation, intake of eggs resulted in higher concentrations of plasma apoA-I (8%) and apoE (17%) with no changes in apoB. Sterol regulatory element-binding protein 2 and 3-hydroxy-3-methylglutaryl-CoA reductase expression were lower with egg consumption by 18% and 31%, respectively (p < 0.05), suggesting a compensation to the increased dietary cholesterol load. Therefore, dietary cholesterol from eggs appears to regulate endogenous synthesis of cholesterol in such a way that the LDL-C/HDL-C ratio is maintained.